The present invention relates to a data holding technology in a storage system, and particularly relates to a data processing system, a storage system, a data processing method, and a computer system in storage systems that use a remote copy technology, in which resources used by a remote copy are reduced during a data-retention period.
In recent years, a computer system has been used widely among business organizations, and importance of data stored in a storage system has increased. Among data stored in a storage system, there are such data which is legally obligated under laws and regulations to be stored for a certain period of time in a state where there are assurances they will not be falsified or altered.
As a method of retaining data for a certain period of time in a state of not being falsified, there is a method in which an exchangeable tape device or the like is used as a memory medium and the memory medium is taken out and kept in a storeroom and the like. On the other hand, in order to retain data for a certain period of time in a storage system such as a disk array, from which a memory medium can not be taken out, some kind of method with which retained data cannot be falsified is needed. As a method to satisfy this need, there is a storage system control method described in Patent Reference 1, for example. In this method, any one of three kinds of access attribute modes of: read/write both possible, write not possible, and read/write both not possible is set to each storage extent in a storage system, and different processing and response to a command from a host are performed in each storage extent in accordance with this setting.
In addition, a technology such as a RAID (Redundant Array of Inexpensive Disks) having a redundant storage extent is employed in a storage system in order to protect stored data. However, with the redundant storage extent in the storage system, there is a possibility that the storage system itself be lost when a large-scale disaster occurs. Then, a storage system is provided with a remote copy technology in order to protect data even if a large-scale disaster occurs. The remote copy is technology in which the storage system itself has redundancy to be disposed in a remote place and data is replicated in the remote storage system (in a copy-destination storage system). Specifically, when receiving a request from a host computer to write data, a copy-source storage system stores the data in its own system and further replicates the data in the copy-destination storage system through a communication line.
Further, as another method in which stored data is in a state of not being falsified, a storage system capable of inhibiting writing is disclosed in Patent Reference 2, for example.
[Patent Reference 1] Published Japanese Patent Application No. 2000-112822
[Patent Reference 2] Published United States Patent Application No. 2004-0268038
According to the above-described technology in related art, writing to a storage extent in a storage system may be inhibited during a data-retention period in order to prevent data stored in the storage system from being falsified. In addition, even if a large-scale disaster occurs, data may be replicated in a storage system disposed in a remote place in order to protect data in a storage system. However, since the writing to the storage extent is inhibited during the data-retention period, there is an inconvenience that resources for performing a data copy to the remote storage system is still used even though the data is not to be copied to the remote storage system.